The present invention relates to hydraulic brake systems for a towed vehicle, and more particularly, to a braking system providing, a controllable braking force proportional to the power input to a hydraulic pressure generator.
Hydraulic brake systems are employed in a variety of towed vehicles including recreation and utility trailers. Conventional hydraulic braking systems in towed vehicles employ a surge brake. The surge brake has a hydraulic piston that controls the flow of hydraulic fluid to the towed vehicle brakes in response to relative motion between the trailer and the towing vehicle. The surge brake is typically mounted on the tongue of the towed vehicle and applies a braking pressure based on the pressure exerted between the towed vehicle and the towing vehicle.
It is generally desirable to control the braking forces that are applied to the towing vehicle and the towed vehicle to reduce disproportionate loads on the respective brake systems. Differences in braking force between the towed vehicle and the towing, vehicle can result in significant problems. If the towed vehicle brake pressure is too great, then the towed vehicle will tend to drag the pulling vehicle to a stop upon application of the brakes. Alternatively, if the towing vehicle braking force is greater, the trailer will tend to over run the towing vehicle.
Therefore, the need exists for a braking system that can be controlled from within the towing vehicle to provide an appropriate braking force. A need also exists for a towed vehicle braking system that can he readily adjusted in response to varying road conditions. The need also exists for a braking system that does not require substantial valving, assembly and maintenance.
The present invention provides an apparatus and method for applying a hydraulic pressure to the brakes of a towed vehicle, and more specifically, provides for applying hydraulic pressure in proportion to a hydraulic pressure generator power input.
Generally, the present braking system includes a hydraulic system and a control system. The hydraulic system includes a hydraulic pressure generator, to which a variable and controllable amount of power is supplied to produce a proportional hydraulic pressure. The proportional hydraulic pressure acts on the towed vehicle brake system to provide a corresponding braking force.
A valve manifold is fluidly connected between the hydraulic pressure generator and the towed vehicle brake system. The valve manifold transmits a hydraulic pressure to the towed vehicle braking system proportional to the hydraulic pressure generator power input. The valve manifold also includes a bleed off capacity for release of the towed vehicle brakes as well as lubrication of the manifold.
A controller is connected to the hydraulic pressure generator for selectively setting the power input and hence hydraulic pressure applied to the towed vehicle brakes.
The present configuration provides a braking force that is completely variable and proportional to a power input to a hydraulic pressure generator. In the hydraulic pressure generator, the hydraulic pressure produced is proportional to the rotational velocity of a motor. The rotational velocity of the motor is directly proportional to its electrical power input. Hence, the hydraulic pressure and the braking force by the towed vehicle brake system are proportional to the electrical power input to the motor.